import java.rmi.*;
import java.net.*;
import java.io.*; 

// This appears in Core Web Programming from
// Prentice Hall Publishers, and may be freely used
// or adapted. 1997 Marty Hall, hall@apl.jhu.edu.

/** An evaluatable version of sin(x). */

class Sin implements Evaluatable, Serializable {
  public double evaluate(double val) {
    return(Math.sin(val));
  }
}

/** An evaluatable version of cos(x). */

class Cos implements Evaluatable, Serializable {
  public double evaluate(double val) {
    return(Math.cos(val));
  }
}

/** An evaluatable version of x^2. */

class Square implements Evaluatable, Serializable {
  public double evaluate(double val) {
    return(val * val);
  }
}

/** This class calculates a variety of numerical
 *  integration values, printing the results
 *  of successively more accurate approximations.
 *  The actual computation is performed on a remote
 *  machine whose hostname is specified as a command
 *  line argument.
 */

public class RemoteIntegralClient {
  public static void main(String[] args) {
    try {
      String host =
        (args.length > 0) ? args[0] : "localhost";
      RemoteIntegral remoteIntegral =
        (RemoteIntegral)Naming.lookup("rmi://" + host +
                                      "/RemoteIntegral");
      for(int steps=10; steps<=10000; steps*=10) {
        System.out.println
          ("Approximated with " + steps + " steps:" +
           "\n  Integral from 0 to pi of sin(x)=" +
           remoteIntegral.integrate(0.0, Math.PI,
                                    steps, new Sin()) +
           "\n  Integral from pi/2 to pi of cos(x)=" +
           remoteIntegral.integrate(Math.PI/2.0, Math.PI,
                                    steps, new Cos()) +
           "\n  Integral from 0 to 5 of x^2=" +
           remoteIntegral.integrate(0.0, 5.0, steps,
                                    new Square()));
      }
      System.out.println
        ("`Correct' answer using Math library:" +
         "\n  Integral from 0 to pi of sin(x)=" +
         (-Math.cos(Math.PI) - -Math.cos(0.0)) +
         "\n  Integral from pi/2 to pi of cos(x)=" +
         (Math.sin(Math.PI) - Math.sin(Math.PI/2.0)) +
         "\n  Integral from 0 to 5 of x^2=" +
         (Math.pow(5.0, 3.0) / 3.0));
    } catch(RemoteException re) {
      System.out.println("RemoteException: " + re);
    } catch(NotBoundException nbe) {
      System.out.println("NotBoundException: " + nbe);
    } catch(MalformedURLException mfe) {
      System.out.println("MalformedURLException: " +
                         mfe);
    }
  }
}